It was another bad week for the west's great Enlightenment tradition. On Monday, the Hungarian government of Viktor Orbán, leader of the highly conservative Fidesz party, introduced its controversial new constitution allowing itself discretionary authority over the media, courts, the central bank and even personal conscience.

There is to be no division of powers in Hungary between the executive, legislative and judiciary; no guaranteed freedom of the press, nor judicial impartiality; no freedom of worship. Abortion and same-sex marriages are outlawed. And echoing other horrific moments from Europe's dark past, Orbán proposes to offer ethnic Hungarians living in neighbouring countries Hungarian citizenship, rather as Hitler did for ethnic Germans in Czechoslovakia.

The European Commission raps the Orbán government for its attack on press freedom and is set to pronounce on whether the wider constitutional changes are compatible with ongoing membership of the EU, with what consequences nobody knows. It is too little too late, testimony to the EU's weakness and lack of grip on what must count as core values in today's Europe.

On Tuesday, the US delivered its own grim echo of Europe's woes. Republican voters in the Iowa caucus delivered an astonishing endorsement of Rick Santorum, an American cut from the same cloth as Mr Orbán. Mr Santorum is as anti-abortion and as anti-same-sex marriage as his Hungarian counterpart, similarly combining aggressive nationalism with ferocious social conservatism, all excused by a twisted understanding of Christianity.

He would use American power to "nuke" Iran if it does not comply immediately with US wishes. He wants to shrink the US state and then organise this shrunken – or as he would say "focused" – government around hard Christian principles, a kind of theocracy. Yet such a man polled just eight votes fewer than Mitt Romney, himself hardly an advertisement for Enlightenment ideas.

The dynamic element on the political right across the west is giving up on the Enlightenment. No longer does it want to embrace tolerance, reason, democratic argument, progress and the drive for social betterment as cornerstones of society. Tolerance is dismissed as an indulgence and a lack of moral standards; progress is trashed as an opportunity for social engineering and a cloak to enhance state power and also as featherbedding the feckless, undeserving poor.

Reason, runs this argument, too often identifies problems that require collective rather than individual responses, amplifying the dread power of the state, and democracy means respecting opponents who have views you consider noxious. Away with the whole damn thought system! Altogether, Enlightenment values are not the reason why the west has advanced so far so fast for the last two centuries and more; rather, they are why the west's economies are in crisis and its societies are fragmenting.

Look at China, continues the argument. It does not worry about press freedom, democracy, respect for dissent, the rule of law or essential human rights. China's growth is driven by millions of unfeatherbedded Chinese compelled to work and organised by one repressive political party. On the right and on the left alike, there is growing impatience with liberal Enlightenment ideals. They get in the way of the party's freedom of action. What matters is belonging to the right tribe – whether that be Hungarian, American or Zulu.

This is very much the position of President Zuma's faction in the African National Congress as the party celebrates its 100th anniversary. Once one of the great forces in the African liberation struggle, it is now competing with Victor Orbán in manipulating a constitution to enlarge the party's discretionary power. Like Orbán, it has taken new powers to muzzle the press and constrain the power of South Africa's courts. Chains of accountability are to be weakened as secrecy laws are strengthened and the anti-corruption agency abolished. The model is the anti-Enlightenment Chinese Communist party championing Han Chinese. An anti-Enlightenment ANC will shamelessly champion its tribe, the Zulu. Reason, democracy, the rule of law and respect for dissent are values of the declining west.

Thus the ANC can cock a snook at the scientific evidence that HIV is linked to Aids. If former President Mbeki, like his successor, believes differently, that is all that matters; everybody knows that science makes mistakes and is not objective. If senior American politicians such as Rick Santorum can argue that the scientific evidence supporting climate change is "junk science" and "an excuse for more government control of your life", then the ANC can dismiss scientific evidence on Aids.

Nor is Britain immune from the same trends. We have our virulent pack of climate-change deniers who insist that what counts is what they believe – and that if science leads to collective state action to manage carbon emissions then necessarily it must be wrong. Eurosceptics come from the same tribal mould; progress is not to build an interdependent Europe. It is the freeze the clock and defend the nation state to the last.

The Enlightenment's defenders are in part to blame for this global rejection of its ideals. Some welfare systems have been ill-designed. Press freedom, as we in Britain know to our cost, has been too easily abused by proprietors furthering their own agenda. Lawyers are paid fortunes to manipulate the letter of the law rather than respect its intent. Scientists too frequently dismiss their own uncertainties.

What's more, progress can be portrayed as a reduction to an exercise in conforming to little more than politically correct protocols. It's why Liverpool Football Club so readily sided with its player Luis Suárez rather than recognise the legitimacy of the FA's eight-match ban for his racist slur.

On issues big and small, we need to get better and cleverer at understanding our Enlightenment legacy and turning it into policies and institutions whose value is obvious to all. The Enlightenment is, with all its imperfections, what drove the rise of the west and will continue to do so if allowed. There is no long-run happiness nor well-being in organising our economies and societies around blood, ethnicity, blind faith and the tribe. The Enlightenment is under siege around the world. It is time to rally to its defence.